The technique of holography has provided a new method for study of environmental situations which heretofore could not be approached. In particular, the possibility of studying the dynamics of particles and fibers in the atmosphere or in a duct by direct observation without the intrusion of measuring devices, now exists. The combination of pulsed lasers with the holographic method will permit a "stopping" or "freezing" of the motion of possible dust pollutants in space, such that their flow patterns can be observed both qualitatively and quantitatively. We are presently using this methdology to determine the speed and mode of fall of fibrous and platy materials (e.g., asbestos, glass fibers, talc, etc.) as they move through space. From this information we expect to establish how the rate and type of movement varies with size, shape, and concentration of particles per unit volume; and compare this with the values obtained using mathematical formulas and experimental data developed previously by others for the movement of particulate matter. Following this, we expect to determine the action of fibrous and platy materials as they move or are drawn to the face of filters of various types at various speeds for the purpose of determining what can be done by varying the rate of air flow through the filter to change this mode of motion for a more efficient collection.